IUU Fishing Effects on the Gender Percentage in Fishing

There are many ways in which human activity affects the population numbers of marine turtles, this includes exploitation of turtles (for their meat, shells and eggs) for cultural and ceremonial practices, destruction of nesting and foraging habitats, pollution, tourism, ineffective management programs and fisheries (Foran and Ray, 2016). Fisheries bycatch represents a significant proportion of global marine catches and therefore has long been implicated in population declines for many species, including that of marine turtles (Humber et al, 2011., Humber, Godley and Broderick, 2014., Temple et al, 2018., Williams et al, 2018). The scarcity of studies into discard rates and survival rates, and lack of accurate information into byactch numbers, make it hard to estimate the levels of incidental catch, and subsequently regulate its effect on population numbers (Humber, Godley and Broderick, 2014., Garcia and Herrera, 2018). It also must be noted that of the studies that do attempt to quantify fishery impact on turtle populations, most are unable to include all the fisheries in the region of study (Garcia and Herrera, 2018). Many studies note the differences in their estimates with previous estimates of IUU fishing effects on turtle (Temple et al, 2018). The lack of standardised collection methods for IUU fishing mean the quality and reliability of reports may also be questionable (Temple et al, 2018). Artisanal and small scale fisheries make up >95% of the worlds fisheries (Temple et al, 2018., West and Mchomvu, 2015) and include 50 million fishers (FAO 2016c). Many of these fisheries are focused in regional areas of developing countries making the collection of data difficult. This results in unreliable or insufficient estimates of IUU fishing. This is a major challenge to overcome when designing and implementing studies into bycatch. One way studies have tried to overcome this difficulty is to collect data through interviewing community members or employing them as observers on vessels. Collecting data this way is low cost and overcomes some of the logistical difficulties, however is it sometimes hard to produce quantitative estimates from the data collected (Humber et al, 2011).

Annually IUU fishing is valued at $23.5 billion (Miller et al, 2019). IUU fishing is an issue present in all ocean basins globally, and effects economic, social and environmental systems (Riskas, Tobin, Fuentes and Hamann, 2018). Incidental catches of turtles can be affected by many factors including fishing technique, population dynamics, and seasonal migrations (Ruiz et al, 2018). Catch of hawksbill turtles is still largely unreported, this may be due to the illegality of catch and the inconvenience caused (Temple et al, 2018). The many gears that are used also make accurate estimations of catch difficult (Temple et al, 2018). To enable local and international governments and organizations to manage the impacts on incidental catch effectively proper data needs to be collected, on; number of vessels, regions of fishing and type of fishing gear used (Ruiz et al, 2018., West and Mchomvu, 2015). In many regions turtles may constitute both target and non-target catch, this may vary by time of year, fisher, or trip (Temple et al, 2018). Small scale/artisanal fisheries are unregulated and poorly documented however, of fishery landings in SWIO small scale fisheries are estimated to account for 75-85% (Temple et al, 2018). Monitoring issues are compounded by migrant fisheries which may take catch in one nation and declare it in another, or neither (Temple et al, 2018). This means ladings data is significantly affected causing management issues, and introducing a need for multinational management initiatives.

The gender percentages in turtle bycatch is also important to study. As many turtles are being caught in nesting seasons this suggests an influx of reproductive females to areas of high fishery activity (Sachithanandam et al, 2015). If the numbers of females dying as a result of fishery interactions is high this could have major effects on the population sizes of future hawksbill populations. Another impact of incidental catch of turtles that needs proper investigation is post-release mortality rate (Garcia and Herrera, 2018). Stress and exhaustion may be caused and injury may be sustained when entangled in fishing gear for prolonged periods of time (one leatherback was hooked for 14 hours but still hauled alive (Poisson, 2010)). Hauling onto vessles may cause injury and stress also effecting post-release survival rates. In many studies, although turtles hauled were observed to be released (Ruiz et al, 2018., Win and Lwin, 2012., Wiadnyana, 2009) usually many would be slaughtered for their meat and shells (West and Mchomvu, 2015), and when turtles are hauled dead the meat is often eaten and carapace sold (Win and Lwin, 2012). Observers also noted that fishers did not know proper techniques to release turtles without causing injury or stress to individuals (Wiadnyana, 2009). It may also be assumed that in periods of heavy fishing and when population numbers are high many turtles may be involved in incidental catches more than once, and the effect of this needs to be studied. It can not be assumed therefore that the mortality rate due to fisheries is equal to number of turtles hauled dead.